In Adobe Photoshop, learn how colors are created and how they relate to each other, which helps you work more effectively.

Understanding color

Knowing how colors are created and how they relate to
each other lets you work more effectively in Photoshop. Instead
of achieving an effect by accident, you’ll produce consistent results
thanks to an understanding of basic color theory.

Primary colors

Additive primaries are
the three colors of light (red, green, and blue) that produce all
the colors in the visible spectrum when added together in different
combinations. Adding equal parts of red, blue, and green light produces
white. The complete absence of red, blue, and green light results
in black. Computer monitors are devices that use the additive primaries
to create color.

Additive colors (RGB)

A. Red B. Green C. Blue

Subtractive
primaries are pigments, which create a spectrum of colors in different combinations.
Unlike monitors, printers use subtractive primaries (cyan, magenta,
yellow, and black pigments) to produce colors through subtractive mixing.
The term “subtractive” is used because the primary colors are pure
until you begin mixing them together, resulting in colors that are
less pure versions of the primaries. For example, orange is created
through the subtractive mixing of magenta and yellow together.

Subtractive colors (CMYK)

A. Cyan B. Magenta C. Yellow D. Black

The color wheel

If you’re new to adjusting color components,
it helps to keep a standard color wheel diagram on hand when you
work on color balance. You can use the color wheel to predict how
a change in one color component affects other colors and also how
changes translate between RGB and CMYK color models.

Color wheel

A. Red B. Yellow C. Green D. Cyan E. Blue F. Magenta

For example, you can decrease the amount of
any color in an image by increasing the amount of its opposite on
the color wheel—and vice versa. Colors that lie opposite each other
on the standard color wheel are known as complementary colors.
Similarly, you can increase and decrease a color by adjusting the
two adjacent colors on the wheel, or even by adjusting the two colors
adjacent to its opposite.

In a CMYK image, you can decrease
magenta either by decreasing the amount of magenta or by increasing
its complement, which is green (the color on the opposite side of
the color wheel from magenta). In an RGB image, you can decrease
magenta by removing red and blue or by adding green. All of these adjustments
result in an overall color balance containing less magenta.

Color models, spaces, and modes

A color model describes the colors we see and work with in digital images. Each color model, such as RGB, CMYK, or HSB, represents a different method (usually numeric) for describing color.

A color space is a variant of a color model and has a specific gamut (range) of colors. For example, within the RGB color model are a number of color spaces: Adobe RGB, sRGB, ProPhoto RGB, and so on.

Each device, like your monitor or printer, has its own color space and can only reproduce colors in its gamut. When an image moves from one device to another, image colors may change because each device interprets the RGB or CMYK values according to its own color space. You can use color management when moving images to ensure that most colors are the same or similar enough so they appear consistent. See Why colors sometimes don’t match.

In Photoshop, a document’s color mode determines which color model is used to display and print the image you’re working on. Photoshop bases its color modes on the color models that are useful for images used in publishing. You can choose from RGB (Red, Green, Blue), CMYK (Cyan, Magenta, Yellow, Black), Lab Color (based on CIE L* a* b*), and Grayscale. Photoshop also includes modes for specialized color output such as Indexed Color and Duotone. Color modes determine the number of colors, the number of channels, and the file size of an image. Choosing a color mode also determines which tools and file formats are available. See Color modes.

When you work with the colors in an image, you are adjusting numerical values in the file. It’s easy to think of a number as a color, but these numerical values are not absolute colors in themselves—they only have a color meaning within the color space of the device that is producing the color.

Adjust color hue, saturation, and brightness

Based on the human perception of color,
the HSB model describes three fundamental characteristics of color:

Hue

Color reflected
from or transmitted through an object. It is measured as a location
on the standard color wheel, expressed as a degree between 0° and 360°.
In common use, hue is identified by the name of the color, such
as red, orange, or green.

Saturation

Strength or purity of the color (sometimes
called chroma). Saturation represents the amount of
gray in proportion to the hue, measured as a percentage from 0%
(gray) to 100% (fully saturated). On the standard color wheel, saturation
increases from the center to the edge.

Brightness

Relative
lightness or darkness of the color, usually measured as a percentage
from 0% (black) to 100% (white).